No, you cannot remove the bushing in the stock prop and use a flo-torq type hub unless the stock prop has a flo-torq hub in the first place.
Any prop that has a flo-torq type hub can be used on any make engine with the proper adapter. Looking at my first post, (the one with the link in it to the Mercury hub) The bottom left piece is the rear thrust washer.. if goes on the propshaft first. Next that black plastic on the top left fits into the inside of the prop from the rear. Then, from the other end of the prop (the side that is furthest away from the outdrive), that brass piece on the top right with the splines on the inside fits into the middle of the prop from that end. Then the whole thing is ready to be slid onto the propshaft and locked in place with the tab washer and the locknut. The diameter of the propshaft and the number of splines on it determine which hub kit you need to use to fit your particular engine, but as long as the prop uses a flo-torq II style hub than any flo-torq II hub kit will fit it.. you just need to use the one for your propshaft.
In your case, you need to use one for a 15 spline Mercury propshaft

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